An apparatus of the kind described above is known in practise. It allows the manufacture of mattress plates from a pre-quilted web which is fed continuously to the apparatus. Two such mattress plates are then connected by means of a circumferential material band known as border in order to form a mattress cover.
The mattress plates which can be produced by means of an apparatus of the kind described above are of rectangular shape with acute corners, since the mattresses used in Europe are usually placed inside a rectangular bed frame and are supposed to essentially fill this frame. However beds in other countries, such as the USA, have a different design. American beds usually include a bed frame which is provided with a wooden floor instead of a slatted frame as it is normally used in European beds. Onto this wooden floor a so-called spring box is placed, on which spring box the actual mattress lies. The spring box contains springs which serve to provide resilience and support to the mattress and thus fulfill the function of the slatted frame common in Europe. Since in this case the mattress is exposed, it is usually provided with rounded corners. Up to now it has not been possible to produce rectangular mattress plates with rounded corners by means of an apparatus of the kind described above.